diff --git a/radio/src/gui/480x272/model_select.cpp b/radio/src/gui/480x272/model_select.cpp
index 2bda99865..4718ea0cf 100644
--- a/radio/src/gui/480x272/model_select.cpp
+++ b/radio/src/gui/480x272/model_select.cpp
@@ -117,7 +117,7 @@ void onModelSelectMenu(const char * result)
   else if (result == STR_DUPLICATE_MODEL) {
     char duplicatedFilename[LEN_MODEL_FILENAME+1];
     memcpy(duplicatedFilename, currentModel->name, sizeof(duplicatedFilename));
-    if (findNextFileIndex(duplicatedFilename, MODELS_PATH)) {
+    if (findNextFileIndex(duplicatedFilename, LEN_MODEL_FILENAME, MODELS_PATH)) {
       sdCopyFile(currentModel->name, MODELS_PATH, duplicatedFilename, MODELS_PATH);
       modelslist.addModel(currentCategory, duplicatedFilename);
       unsigned int index = currentCategory->size() - 1;
diff --git a/radio/src/sdcard.cpp b/radio/src/sdcard.cpp
index 39e409672..3692cb4f0 100644
--- a/radio/src/sdcard.cpp
+++ b/radio/src/sdcard.cpp
@@ -75,20 +75,33 @@ char * getFileIndex(char * filename, unsigned int & value)
   return filename;
 }
 
-int findNextFileIndex(char * filename, const char * directory)
+uint8_t getDigitsCount(unsigned int value)
+{
+  uint8_t count = 1;
+  while (value >= 10) {
+    value /= 10;
+    ++count;
+  }
+  return count;
+}
+
+int findNextFileIndex(char * filename, uint8_t size, const char * directory)
 {
   unsigned int index;
   char * indexPos = getFileIndex(filename, index);
   char extension[LEN_FILE_EXTENSION+1];
   strncpy(extension, getFileExtension(filename), sizeof(extension));
-  do {
-    char * pos = strAppendUnsigned(indexPos, ++index, 2);
+  while (1) {
+    index++;
+    if ((indexPos - filename) + getDigitsCount(index) + LEN_FILE_EXTENSION > size) {
+      return 0;
+    }
+    char * pos = strAppendUnsigned(indexPos, index);
     strAppend(pos, extension);
     if (!isFileAvailable(filename, directory)) {
       return index;
     }
-  } while (index < 99);
-  return 0;
+  }
 }
 
 bool isExtensionMatching(const char * extension, const char * pattern, uint8_t flags)
diff --git a/radio/src/sdcard.h b/radio/src/sdcard.h
index a64cd114a..a2269fd62 100644
--- a/radio/src/sdcard.h
+++ b/radio/src/sdcard.h
@@ -125,7 +125,7 @@ T * getFileExtension(T * filename, int size=0)
 #endif
 
 bool isFileAvailable(const char * filename);
-int findNextFileIndex(char * filename, const char * directory);
+int findNextFileIndex(char * filename, uint8_t size, const char * directory);
 
 const char * sdCopyFile(const char * src, const char * dest);
 const char * sdCopyFile(const char * srcFilename, const char * srcDir, const char * destFilename, const char * destDir);
diff --git a/radio/src/storage/sdcard_raw.cpp b/radio/src/storage/sdcard_raw.cpp
index b27e2a211..6fa6e4eb7 100644
--- a/radio/src/storage/sdcard_raw.cpp
+++ b/radio/src/storage/sdcard_raw.cpp
@@ -218,7 +218,7 @@ const char * createModel()
   memset(filename, 0, sizeof(filename));
   strcpy(filename, "model.bin");
 
-  int index = findNextFileIndex(filename, MODELS_PATH);
+  int index = findNextFileIndex(filename, LEN_MODEL_FILENAME, MODELS_PATH);
   if (index > 0) {
     modelDefault(index);
     memcpy(g_eeGeneral.currModelFilename, filename, sizeof(g_eeGeneral.currModelFilename));